Spatiotemporal Variations in the Water Storage of Closed Lakes on the Tibetan Plateau and Their Climatic Responses from 1976-2013

The water storage of lakes responds sensitively to variations in climate. At the same time, lakes have an important influence on climate by altering the energy exchange between the land surface and the atmosphere. In the present study, water storage changes in 114 closed lakes with areas greater than 50 km2 on the Tibetan Plateau (TP) were estimated by integrating SRTM DEM (Shuttle Radar Topography Mission, Digital Elevation Model) and LandSat images. The results reveal that the total water storage increased by 102.64 Gt from 1976-2013, a rate of 2.77Gt•yr-1. Specifically, the storage changes between 2000 and 2013 account for 97% of the changes during the entire study period, resulting in an overall positive water balance of 7.67 Gt•yr-1. However, the pattern of water balance changes of the studied lakes exhibit significant differences from 1976-2013, and four main patterns were distinguished by using k-mean clustering analysis: a slightly increasing followed by a rapid increase (the southeastern part of the endorheic region of the TP); an initially decreasing water balance, followed by an increase from 1990 (the center and west part of the endorheic region); an initially decreasing, but followed by an increase from 2000 (the northeast part of the endorheic region); and a mainly decreasing water balance (the southern outflow region of the TP). Precipitation was the dominant factor affecting changes in lake water balance; in particular, a large precipitation increase resulted in a dramatic increase of lake water storage from 2000-2013. The relative influence of temperature was opposite before and after 2000. In addition, water storage changes of lakes with and without glaciers melt water input were compared and the results show the influence of glaciers varied. Distinct regional patterns in water storage change indicate clear differences in the climatic sensitivity of lakes in time and space. The findings have important implications both for the interpretation of past lake level records and for the prediction of future lake responses to climate change.